Cato? or Flowerpot efect

[MWJ]

Can someone please enplane what exactly happens during a cato? when a shell explodes in a launch tube. Does it destroy the tube sending pieces of ABS plastic everywhere or does it exhaust the gas's and energy out through the opening of the tube? I just want to know what to expect when or if this happens.

Your knowledge and experience is our tools to learn and stay as safe as we can.

 

Thanks Guys

[ivars21]

It really depends from the mortar, from the burst charge for the shell etc. Fibreglass usually tends to flowerpot well (mortar is still usable afterwards), the same with hdpe. Although if you get flowerpot from salute shell, most likely it will destroy the mortar. And then again, it depends from mortar wall thickness, shell size etc, for small shells even cardboard mortars are still usable after flowerpot.

Edited February 1, 2014 by ivars21

[asdercks]

CATO: catastrophe at take off, some of my rockets have exploded at take off because the black powder wasn't compressed really well, leaving gaps in between the grains of powder.

You should avoid using ABS pipe as it can throw sharp shrapnel if it explodes. hopefully a more advance member will give you a more detail answer than mine. lol.

[pyroman2498]

when a rocket cato's it can be caused by multiple things , a uneven grain, crack in the grain , to fast of powder for your clay bulkhead to handle , Ect these can be interesting on them self's , but can get out of hand real quick.. Flower pots happen when a shell explodes in the mortar, most of the time causing the stars and such to rise out of the mortar causing a mine type effect. with larger shells , if they flower pot they could easily split the mortar sending stars flying at everyone. On large shells , the mortar is put in the ground , this is to protect the mortar from splitting , and avoid people getting hit by anything if the shell does explode ( although its not full proof it does help , but accidents do happen ) , as with what happens to the mortar when a shell flower pots is a case by case basis , usually it just turns you hard work into a mine , but sometimes it will split your tube ( if your using proper mortars * steel is an acceptation to this . your mortar will just split like running a knife down paper and it might be bloated a bit , I say steel is an acceptation because a steel pipe flying , I dont care who you are, is a scary thing to see and can cause just as much damage, if not more, as a improper pipe , Which include but are not limited to **, PVC ,LDPE , arrogation piping , or most any other pipe that you would most likely find at you Home depot or lose ) . hope this somewhat answers your question

 

Stay Safe and Stay Green

 

~Steven

[pyrokid]

Firework mortars should be made from HDPE, fiberglass, paper, or buried steel.

 

If proper setback distances are observed, the chance of being hit by shrapnel is reduced drastically.

 

PVC can be used for rocket racks on the condition that the motor sits outside the tube at all times.

[nater]

A CATO is typically in reference to a rocket failure - Catastrophe At Take Off.

 

A Flowerpot is when the shell's burst ignites at the same time as the lift. This usually results in a mine shape, but if the shell has a strong break it can cause the mortar to fail.

 

A Muzzle Break / Blast is when the shell breaks as it is leaving the mortar. This is usually a flaw that causes the time fuse to burn too fast or something that caused a tiny delay from a flowerpot. To the observer, this looks a little different as the flower of the shell is all over the ground rather than directed upwards like a flowerpot.

 

A low break occurs when a shell has too little lift, is too small for the mortar or if the lift is bad. This can break low or return to the ground and break.

 

The picture below was a 2.5 Chinese Salute that blew in an HDPE mortar. The salute that failed was the second in a chain. The rack was a 3-way fan with one chain in each angle of the fan. Each chain was in a single rack, as opposed to being snaked across the fan. (different effect, neither method is right or wrong) This rack was on the outside of the fan. The rack failed, scattering the tubes with live shells with hot leaders. The failure only destroyed one rack, with no damage to the other two in the fan. As you can see, the HDPE mortar is heavily damaged, but did not break apart into any significant amount of shrapnel. This is the biggest advantage to HDPE.

 

I have seen fiberglass mortars fail into sharp pieces. However, the material is light enough that the pieces did not travel far or have enough momentum to cause serious damage. PVC and other plastics are dense and brittle enough that they should be avoided. Steel mortars can cause MAJOR damage and pose a significant risk to the crew of a show. They should only be used for heavy shells that cannot be lifted safely in HDPE mortars. Per 1123, multi-breaks are to be fired out of steel. When used, steel mortars cannot be racked and should be buried 2/3 of their length deep. I prefer extra setback and e-firing only when using steel mortars. There are promising tests being done to make steel mortars unnecessary, even for large multi-breaks.

 

[Nessalco]

A couple years back we had a 3" Titanium salute go off in a fiberglass gun, on a handlit show. It required surgery to get all the fiberglass out of the shooter's leg and butt. He was wearing bunker gear, and it cut right through. Of course, he was only ~10' away when the shell let go.

 

Kevin

[Mumbles]

This page on pyrouniverse shows a side by side comparison of PVC and HDPE. ABS will act similarly to PVC.

 

http://www.pyrouniverse.com/FAQ.htm#9

 

It's pretty easy to find relatively inexpensive mortars online. I'd be happy to point you in the right direction if you'd like. If you're looking for 2" mortars, be aware that there is a difference between actual 2" and the nominally 2" tubes used for class C shells.

 

All the mortar types have their advantages. I've long been a proponent of HDPE and steel when necessary, but have been warming up to fiberglass. I was trying to find an image of a failed fiberglass mortars, but couldn't find one. Generally they sort of feather and tear apart, but don't really fly far. As Nessalco pointed out, it could still cause issues if you're close by. Paper or cardboard generally turn into confetti. HDPE usually either fails by splitting or tearing sort of like a banana, as you can see above by Nater. It also can tear or bust out the wooden plug in the bottom. Steel generally tears or splits, but does have the capability to make shrapnel. Here's an image of of a steel mortar failure courtesy of one of our members.

 

[nater]

I was unfortunate enough to be on a B line when a large multibreak with a 10lb bottom shot failed in the mortar. It left a crater deep enough to stand in and drove part of the mortar underground. We never found enough steel to account for the entire mortar either.

 

Expanding on Mumbles' comment regarding HDPE and Fiberglass, you should be aware that HDPE warms up and softens with repeated firing. I feel that in a club event where you might be reloading many times during the evening, that fiberglass is a better choice. Another advantage to fiberglass is that mortars that are close to the same size are often produced in different colors. This makes it easier to load the proper sized shell when it is dark.

 

For commercial shows where each shell has its own mortar, HDPE seems to be more durable when racks are tossed around while setting and tearing down a show. I think they are also slightly safer when handlighting for the reason Nessalco pointed out. On commercial displays it is common to be very close to the shells you are lighting.

[MWJ]

When I saw a HDPE mortar tube on the net and it looked like ABS. So I thought that's all it was so I used a piece of 2" ABS for my tube. Mumbles, If you can point me in the right direction for a good inexpensive tube I would like that very much, thanks.

(Nater: I was unfortunate enough to be on a B line when a large multibreak with a 10lb bottom shot failed in the mortar. It left a crater deep enough to stand in and drove part of the mortar underground.) Sounds like a satchel charge I played with in the USMC. They make good tank traps! But that's NOT what I want in my back yard.

 

Thanks guys, this help a lot!

[nater]

Http://www.rtpyro.com . Great guys with a great product and service.

[marks265]

This page on pyrouniverse shows a side by side comparison of PVC and HDPE. ABS will act similarly to PVC.

 

http://www.pyrouniverse.com/FAQ.htm#9

 

It's pretty easy to find relatively inexpensive mortars online. I'd be happy to point you in the right direction if you'd like. If you're looking for 2" mortars, be aware that there is a difference between actual 2" and the nominally 2" tubes used for class C shells.

 

All the mortar types have their advantages. I've long been a proponent of HDPE and steel when necessary, but have been warming up to fiberglass. I was trying to find an image of a failed fiberglass mortars, but couldn't find one. Generally they sort of feather and tear apart, but don't really fly far. As Nessalco pointed out, it could still cause issues if you're close by. Paper or cardboard generally turn into confetti. HDPE usually either fails by splitting or tearing sort of like a banana, as you can see above by Nater. It also can tear or bust out the wooden plug in the bottom. Steel generally tears or splits, but does have the capability to make shrapnel. Here's an image of of a steel mortar failure courtesy of one of our members.

 

That was an 8 inch mortar which has about a .330 wall thickness. That pic is from crater night at PGI where a 3 break shell had its way with the mortar. We put our shells apart from others to avoid other peoples problems such as this. I have a pic of the after math of the competition shooting line but it is pretty blurry so I never posted it. It basically unplanted all the other 8 inch guns that were about 4 feet or more in each direction and sloped from the point of origin. Luckily they were empty at the time. With all the loose ground from planting the mortars it is real easy to upset a line of mortars. Luckily this was the last of three shells of mine which did make for a bit of a coup de gras. We sure did beat the containers up that week at the PGI from one end to the other that year. Fond memories for me and is why I posted it.

 

When this mortar met its maker it did fail at every weld applied to the pipe. This particular mortar is constructed from schedule 40 pipe which is common to use. It has a welded seam that travels the length of the pipe when originally made. When constructed into a mortar for our use the weld seam is ground smooth on the inside of the pipe. Otherwise there is a nasty weld joint on the inside that is not favorable for shooting shells from. After the pipe is cut to length and the weld ground smooth the plug is welded in the bottom. This is why the mortar that I originally posted looks so "square", it ripped all the weld joints open and laid it out almost flat. When looking at the picture you can count the breaks.

 

Don't ask me how I know so much about that picture

 

Mark

[Mumbles]

Most of my HDPE mortars come from Kastner. http://www.kastnerhdpemortars.com/ I've seen plenty of R&T's mortars at club shoots and they're great too. I'm kind of picky when it comes to HDPE. I only buy and use mortars that use screws or bolts to attach the wooden plug. Both Kastner and R&T do this for all sizes of mortars as far as I know. A lot of other people use staples, at least in the smaller calibers. Conveniently, the above two outfits are also generally the same price or cheaper than most of the guys I'm aware of selling the stapled ones.

 

For fiberglass I'd suggest either ACE (http://www.acepyro.com/Shop/Equipment) or ATF (http://www.acepyro.com/Shop/Equipment). ATF sells both types actually, but a little more expensive than the above suppliers.

[schroedinger]

Also maybe have a look at pyroboom. Displayfireworks1 just uploaded a video on them yesterday (youtube), giving instructions on how to get a good promotional discount.

[nater]

Pyroboom has good service. He only offers consumer and 3" sizes, the plugs are stapled. R&T or ACE will carry everything you might need.

[nater]

Mark,

 

Did your pictures look similar to these?

 

This was not either incident that I mentioned above.

 

 

Edited February 2, 2014 by nater

[marks265]

Nater,

 

Yep, that's me! The top pic is what I was trying to describe as I remembered it from my aftermath of the pic that Mumbles posted. As I mentioned above my pics were pretty blurry so thanks for that!

 

The bottom pic shows a muzzle break from a 12" shell in the foreground. You can see what approximately 1" stars will do to a metal container let alone the blast itself. Note that the mortar and surrounding area are intact in regard to the immediate area of the mortar. The shell broke exactly upon exit of the mortar.

 

In the background you will see the splashing from my 8" against the containers. This is an extreme case flower pot. The shell held more material than the mortar could handle when the shell came unglued in the mortar and blew up.

 

CATO's are for rockets and yes I've had a few of those too

 

I do have to mention that this is also the same night that I won Best (and worst) Exhibition Cylinder shell competition at PGI. I also had a third shell which came apart in the air. My problem was that there was two more feet of mortar than I was used to shooting from. It made a big difference. This year I'll be back and ready for it.

 

Thanks Nater.

Mark

[MWJ]

Great information guys, thanks! I like to know what to expect just in case. Thanks for the web sites too. I guess I have to go shopping for some Safe tubes. I already plan on building a blast wall behind my launch (Mortar) tubes. I'm not ready to display for people, YET! Someday though. I can't lite anything off in the summer months here in North eastern Wash. so that will be my learning time.

 

Mike

[nater]

I thought I had a picture of the rocket rack that was destroyed on what I think was the same day too. Someone had a 6lb go in a rack that was only about 30 ft from the ready box. I was getting my next rocket out when it went. I think i jumped back all the way to peanut gallery in one leap.